#include <stdio.h>

int min(int x, int y){
    return x<=y?x:y;
}

int main(){
    int n;
    printf("Enter a number: ");
    scanf("%d",&n);
    int result=min(n,0);
    if(result>=0){
        printf("yes\n");
    }else{
        printf("no\n");
    }
    return 0;
}
